The present invention relates to an anti-siphoning device for preventing the siphoning of gasoline. More particularly, the present invention relates to an anti-siphoning device for gasoline tanks, the device being designed to fit the majority of automobiles presently on the market, including those fitted with baffles, and having improved features for preventing the siphoning of gas, while at the same time preventing friction between the various components which could result in the production of sparks.
Previous devices for preventing the siphoning of gasoline from automobile gas tanks have included cone-shaped spring devices such as those described in U.S. Pat. Nos. 1,925,079, 2,133,520 and 2,496,992, in which the cone-shaped device is attached near the outer rim of the gasoline fill pipe. In other prior art devices, such as those described in U.S. Pat. Nos. 2,007,805, 2,017,837 and 2,009,558, the spring portion of the device is located farther down the fill pipe at a point removed from the outer rim of the fill pipe. It has been found that the use of such prior art devices has not altogether resulted in preventing the tank from being siphoned, since a properly shaped siphon tube may penetrate between the coils of the spring of these prior art devices. In addition, it has been comparatively simple to remove the prior art devices, by the use of a screwdriver or similar means. Due to the interrelationship of the various components of these prior art devices, there is also an opportunity for sparking created by the sharp edge of one component striking the edge of another component.
By the present invention there is provided an anti-siphoning device in the form of a one-piece spring construction, the device of the present invention having features which effectively prevent removal of the device from the fill pipe of a gasoline tank, once the device has been installed. Furthermore, the construction of the anti-siphoning device of the present invention has been found to provide improved characteristics for preventing the insertion of a siphoning tube into the fill pipe of a tank which has been fitted with the device of the present invention. In addition, the construction of the present anti-siphoning device has been found to prevent the occurrence of sparks between components of the device. The anti-siphoning device of the present invention is of a shape which will fit the fill pipes of most modern-day automobiles, including those having fill pipes which are fitted with baffles.
The anti-siphoning device of the present invention includes a one-piece spring having an upper portion coiled in a cylindrical shape and a lower portion having the general shape of a cone. The cylindrical-shaped portion is formed of a series of contiguous or "kissing" coils, with at least six of such contiguous coils being present. The cone-shaped portion, which begins immediately below the lowermost contiguous coil of the cylindrical portion, is also provided with a series of contiguous coils at its lower end. At least four such contiguous coils are present in this position at the lower end of the cone-shaped portion. The lower end of the cone-shaped portion is provided with a bend so that the contiguous coil portion at the lower end of the spring projects outwardly at an angle of approximately 45.degree. from the vertical axis of the device. Such features have been found to provide a highly secure fit for the spring in the neck of a fill pipe. This arrangement also provides improvements in preventing the insertion of a siphoning tube.
The extreme tips at both the upper and lower ends of the spring which make up the present device are curved inwardly away from the adjacent coils, in order to avoid the sparking tendencies which have been characteristic of prior art devices. In addition, a definite gap or space is provided between the tips of the spring and the adjacent coils to assist in preventing sparks.